Human evolution has just gotten a lot more complicated with the discovery of a new species in South Africa, and cave divers Steven Tucker and Rick Hunter are the source. The findings that came about from their journey of cave diving has brought about the unveiling of Homo naledi. With its unusual combination of features and its unknown place in the evolution of humanity, Homo naledi is stumping researchers in where exactly it is located in the timeline. Another question and discussion are what exactly “the dawn of humanity” has in store for the future and the past of humanity.
South Africa is known as the Cradle of Humankind, where the first uncovering of humanity started. On Tucker and Hunter’s journey through Rising Star, a cave system 30 miles northwest of Johannesburg, they stumbled across Homo naledi. Its specific location was constricted further in the cave system because of a narrow tunnel called Superman’s Crawl – since one cannot pass through without carrying the pose of the man of steel in flight. Lee Berger, a paleoanthropologist (anthropologists who study ancient human remains) who commissioned many of these findings took teams of archeologists to find more pieces of the human fossils. To speed up the research and ability to inform those in the science field about the discovery, 50 people studied the sets of bones in a six week period of time. The overall haul-in for all of the bones came in with fifteen partial skeletons, varying from infant to elderly. There were four partial skulls – thought to be two male and two female – and with the teams of researchers reconstructing the bones, there were a mesh of shocking findings. The skeletons appearance have apish shoulders, a flared pelvis, and a skull that indicates the brain size is half the size of a human’s, while the bottom portion of the pelvis is modern and human-like. Homo naledi’s upper features are similar to apes while its lower features are similar to humans, making this species a transition species.
Unfortunately with Homo naledi being revealed in a cave underground, there are many issues about the approximate age of the skeletons are. While most discoveries are carbon dated and dated through the use of layers of rocks and the location of the bones, having Homo naledi within a cave makes it exceptionally difficult to put at date to it. The possibility of falling into the cave from varying time periods to turning the cave into a burial ground centuries later makes scientists unable to put the Homo naledi on the human evolution timeline until another more solid discovery of other Homo naledi bones can be found.
With Homo naledi not yet having a spot in chronological listing of the human evolution, some of those that have been discovered go as following: Ardipithecus ramidus, Australopithecus afarensis, Homo habilis, Homo erectus, Homo neanderthalensis, and finally Homo sapiens.
Ardipithecus ramidus is estimated to be 4.4 million years old and was first discovered in Ethiopia in the 1990s. Its bone structure indicates how this species is tree-climbers with partial bipedal behaviors. There is little difference in size between the male and female bones that were found. With sharp canine teeth prevalent in the skeletal reconstruction, this species is the earliest ancestor of the Homo genus since it is ape-like in appearance.
Australopithecus afarensis is estimated to be 3.9-2.9 million years old and the first skeleton found was named “Lucy” when it was discovered in East Africa. Appearance-wise, “Lucy” has both human and ape characteristics: with an ape-shaped face and long, strong arms speculated to be used for climbing trees. Its structure allows it to survive on both the land and in the trees, and its brain size is a third of that of a human brain. Australopithecus afarensis is extremely important to the species tree since it is the final branch before the path diverges into the Australopithecines and the Homo, though if Homo naledi is categorized in this period then both of these branches will be important to the split and divergence of the genus.
Stepping away from the Australopithecines branch, the first of the Homo branch is the Homo habilis, which is estimated to be 2.8-1.5 million years old. It diverges from the other branch because of small details that bring it closer to the modern human bone structure. Smaller teeth rather than teeth associated with apes and chimpanzees is the major difference since its structure and features are still very primitive with long arms.
Homo erectus is estimated to be 1.9 million years old to an uncharted gap between its overall estimation. One specific skeleton is nicknamed “Turkana Boy,” its body is similar to a modern human, but with some exaggerated features. Homo erectus has elongated legs and short arms with a stubby torso to go with this mismatch ensemble of humanlike body parts. Through looking at other fossils at this time period and the wear-and-tear of the bones of this species, it is evident that they are recorded to have the earliest usage of tools, such as creating hand-axes.
Homo neanderthalensis is estimated to be 200,000-400,000 years old. Ironically enough, these are the species that have been dubbed ‘Neanderthals’ in pop culture from movies to fiction. Thought to have inhabited areas of Eurasia, the ‘Neanderthal’ has an appearance that is shorter and more muscular than the modern human. Through skeletal reconstructions, the brain is also slightly larger.
Finally the species within the evolutionary chart that is what humans are today are Homo sapiens, having an estimated time of 200,000 years to the present time. As evolution has shown, humans have went through a great deal of changes to become the species it is today. And whether it is just speculation or reality, the human genus continues to expand with new findings and unearthing ancient bones. While Homo naledi is still not completely classified, it had brought up many questions for scientists, and could have the potential of changing the outlook of the ever-expanding evolutionary chain.